You don't cut the leaves at all at this stage - the leaves tend to be dying back by the time they flower, and many people remove the leaves once they are in flower, but you don't have to.

I noticed this question, I planted some nerine bulbs in pots and they seem to be growing well, will they be ok left in pots and when should they flower?

I planted nerines last year in a sunny spot but had foliage but no flowers. After reading that they may not flower in the first year I decided to leave them and I have plenty of foliage this year which is just starting to yellow ,which didn't happen last year so am hoping for flowers in September.

Andrea - I've had Nerines in a pot on my southfacing balcony for the last 16 years and they flower every year. Haven't repotted for at least five years either, I really must get round to splitting them and repotting.

I've had them in pot for a similar time and only repotted once. I just feed them a few times in the summer when the leaves are there but apart from that I do nothing and there are more flowers every year - 13 last autumn from on original 6 bulbs.
The leaves on these have always been gone by the time the flowers appear and I've never removed them before that. The pot is in a sheltered south west facing corner between house and conservatory.